1. Field of the Invention
The present invention relates to the field of protein purification. In particular, the subject of the present application is a process for a baseline separation of the antithrombin III variants xcex1 and xcex2.
2. Description of Related Art
One of the most challenging analytical tasks in modern bioanalysis is still the separation and characterization of proteins and peptides. The difficulties mainly derive from the complex structure of proteins, requiring several analytical techniques to get sufficient information. Conventionally used methods for protein separation are SDS-PAGE, SEC, MS, RP-HPLC etc. (ref. 1).
Although several modes of high performance liquid chromatography are well established, capillary electrophoresis (CE) and its different modes, namely capillary zone electrophoresis (CZE), SDS molecular weight capillary electrophoresis, capillary isolectric focusing (CIEF), capillary gel electrophoresis (CGE), and last, but not least, micellar electrokinetic chromatography (MEKC) are rapidly gaining in acceptance (2).
Concerning the plasma glycoprotein antithrombin III (AT-III) which is responsible for thrombin inhibition in the blood coagulation cascade, a special analytical problem lies in the fact that it consists of two variantsxe2x80x94the xcex1- and the xcex2-formxe2x80x94which are different in their affinity to the polysaccharide heparin. The availability of a reliable method to quantify AT-IIIxcex1 and xcex2 in, for example, plasma-derived concentrates and body fluids, will help to elucidate the currently not fully understood existence of the two isoforms.
In order to define the quality of AT-III, it is therefore meaningful to characterize it by the measurement of its portions of the xcex1- and xcex2-variants and to develop methods for their separation.